There is evidence that the changes in pancreatic water, electrolyte, and protein secretion in humans with pancreatic cancer may be due to specific effects of the carcinogen(s) on the secretory cells. If this is so, these changes may actually precede the development of grossly evident neoplasm. Using the Syrian Golden hamster with induced pancreatic cancer the abnormalities in pancreatic secretion and the mechanisms responsible for them will be investigated. Standard laboratory techniques as well as pancreatic micropuncture will be employed. In the first phase of this work the characteristics of secretion in the unstimulated and then the secretin and CCK stimulated normal hamster pancreas will be determined. In the second phase similar experiments will be performed on carcinogen-treated and control animals and the characteristics of secretion in animals with pancreatic cancer will be determined and compared with the normals. In the third phase the mechanisms responsible for the alteration of secretion in pancreatic cancer will be investigated. The effects on pancreatic secretion of partial pancreatic duct obstruction in the absence of carcinogen will be determined. This will involve a measurement of intraductal pressures during secretion and a correlation of these findings with alterations in secretion. These studies will allow a determination of whether the secretory changes associated with malignancy are due to a direct toxic effect on the secretory cells by the carcinogen(s) or are a non-specific effect, associated with partial duct obstruction from the tumor.